we're kind of unofficially keeping track of what numbers have what problems.
they weren't all made at the same time during the same run.
as i compared my 34xxx to my friends 15xxx, it was immediately obvious to the naked eye that the 34xxx casting of the sub frame was much "nicer". finer grain, less pocket, crisper edges etc..
it seems to me that the 34xxx are the ones having trigger reset problems.
26xxx being between 15xxx and 34xx might have been an attempt to improve on the metalurgy or machining process.
obviously none of this fixes your gun (sorry to say) but... there have been a couple of guys who sent their pistols in and got some repair work done. you've certainly got a candidate for some special attention from the customer service department.
as an aside (and more unpleasantness) check the plastic frame. as you look in the top of the frame with the slide off, there are two square pieces of plastic that the front of the trigger group dogs against. the guide rod goes between these two pieces of plastic. these two pieces of plastic are known to break in s40 s. if you see cracking in the pieces of plastic, try to get a new frame too.
it happens when the slide batters these pieces of plastic during recoil.
s40s have a cut that m9s don't (don't know about m40 or s9)
with the slide off and the barrel removed, look at the muzzle end of the slide exactly where your crack is. on the back side of that crack you'll most likely see where some metal has been removed. say 20 thousandths. m-9s don't have this. this is where the slide slams into plasic pieces during recoil, and also where steyr took out some frame rigidity shortening the barrel length. i think steyr knew they were cutting it close in this measurement, even with removing material from the slide. you might even notice more than 20 thousandths, as they could have attempted a deeper cut to lessen the chance of recoil causing a cracked frame.
i thought about grinding another ten thousandths off of mine to keep it from happening, but seeing your slide break certainly dissuades me.
just thought you should check now cause you might be in line for new...everything.
hopefully the s40 a1 will be more sorted out. to me it's the best combination of everything i was looking for.